Making paper board



Nov. 29, 1932.

c. L., KELLER MAKING PAPER BOARD Filed Sept. 13, 1929 INVENTOR.

ATTORNEY-5'.

Patented Nov. 29, I932 CHARLES L. KELLER, OF CINCINNATI, OHIO,

ASSIGNOR TO THE RICHARDSON COMPANY,

MAKING PAPER BOARD Kiiplication filed September 13,4929. Serial No. 392,370.

My invention relates to the formation of paper board in plural plies which is pasted together by using asphalt or similar bituminous or heat In making such boards the inner ply may be a board which has been coated with the bituminous substance, it may be saturated and coated with the substance, or it may have a structure and composition within which is retained a large -or small proportion of the same ?or a different bituminous substance or waterproofing agent.

The difliculty encountered in making boards using a central ply or more than one inner ply, the whole being cemented together with asphalt or other bituminous or heat plastic binder, is that the product tends't'o warp after it has been completed. This warp- 1 ing is quite undesirable, and in the making of panel board renders the board very unsatisfactory. I

I have discovered a mode of utilizing a bituminous cementing agent in making plural ply board which overcomes this defect in the product, which is here concerned.

I accomplish my object by that certain mode of procedure of which an'example is to be fully described,'reference being bad to the accompanying drawing, and the novelty of which process will be duly set forth in the claims.

- In the drawing the figure is a dia ram of a mechanism which may be used in Forming asphalt pasted plural ply board.

In connection with the description of the example of my process which follows, it may be'pointed out that I attribute the reason for board, to the fact that the application of hot asphalt to the sides of the inner ply makes it very hot, and since the pasting has always been done while the asphalt is still molten, the front boards and back boards are united with the central board or boards when the former are cool and the latter are hot. When the structure cools, the inner board or'boardswill shrink and the adhesive joint-serving to retain the parts together, the outside boards will warp. -The process whichI employ permits the plastic medium for the pasting."

inner board or boards to become cool, so that the bituminous coating becomes hard or partially hard, I then apply a solvent for the coating .which makes the surface soft and adhesive, and then apply the front and back boards, and if more than one center board is em loyed, unite, the center boards together. n the process which I will describe, I have employed in practise a single inner board which is formed of a fibrous structure in which asphalt is incorporated prior to the formation of-the sheet. 7 Such a sheet of material is illustrated at 1, andthe outer sheets are indicated at 2 and 3, these being of any preferred structure.

Ihave indicated at 4; the concluding rolls of a coating machine or saturatingmachine through which the sheet 1 is passed or by means of which the surfaceson both sides of the central board have been coated with hot asphalt. I have indicated at 5 a supply roll for the sheet 2, which sheet is fed along by means of the rolls. 6. I have indicated a a supply roll for the sheet 3.-

At 8 I have indicated a series of rolls between which the several sheets are passed and by means of which they are pressed together.

At 9 I have indicated spray pipes in which benzine or other solvent for asphalt is sprayed upon both sides of the central sheet.

At 10 are illustrated a pair of rolls for smoothing outthe asphalt coating imparted to the sheet 1. The space between the rolls 10 and the spray pipes 9 is gauged so that. the sheet which has been coated will have time to cool in it's travel. If necessary, air blowers'or the like maybe applied .at this space. thewarping of asphalt pasted panel or like In the process using the mechanism just described, the sheet 1 coated with asphalt on both sides and very hot as a result, is passed between the smoothing rolls, and then through a space during which the sheet cools and the asphalt hardens. The asphalt is then sprayed with benzine with the result of cooling further, and in addition making the 95 surface of the coating quite tacky and suitable for pasting, WlllCll it would not be at the reduced temperature which it has at tained. The front and back sheets are led so that they contact the sheet 1, and th -1 three sheets are fed together between the pressing rolls 8, thereby uniting the sheets together with a board. The board so formed will not warp as is l the case with boards which are united by the use of asphalt as an adhesive when the asphalt and hence the sheet upon which it lies is hot.

As was noted, the essence of the method 1 could be practised with a number of inner plies as well as with a single one, althou h this would not be regular practise. In t e claims, however, when referring to a central sheet, I wish to include one which is made of one or more pieces.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is 1. That method of uniting outer sheets to an inner sheet which consists in coating the inner sheet with a heat plastic binder while said binder is hot and non-solid, cooling the coated sheet, softening the coating by means of a solvent, and then applying the outer sheets to the inner sheet.

2. That method of uniting outer sheets to an inner sheet which consists in coating the inner sheet with a bituminous binder, cooling the coated sheet, softening the coating by means of a solvent, and then applying the outer sheets to the inner sheet.

3. That method of uniting outer sheets to an inner sheet formedof fibre with bitumen incorporated therein, which consists in forming a plastic bituminous coating on said sheet while same is hot, cooling the sheet, softening the coating with a solvent, and then applying the outer sheets to the inner sheet.

4. That method of making panel board 49 which consists in forming a coating of hot asphalt on both sides of an inner sheet, cooling the sheet, applying a solvent to the coating on the sheet, and uniting the sheet with outer plies to be bound thereto by the said coating.

CHARLES L. KELLER. 

